What is the value of available risk-scores in predicting postoperative complications after aorto-iliac surgery? A prospective non randomized study.

AIM

With an aging population, atherosclerotic manifestations are steadily increasing. Beside the anatomical and pathophysiological preoperative risk-factors accompanying perioperative risk-factors like patient's age, length of operation, blood loss and skill of the surgeon, all need to be accounted for when assessing the risk of morbidity and mortality after vascular surgery. The demand for cost effectiveness may make a risk-score system useful. The aim of the present study was, therefore, to prospectively apply various scoring systems in order to estimate outcome in patients undergoing aortobifemoral surgery due to arterial occlusive disease at the aorto-iliac level.

METHODS

A prospective non randomized study was carried out. The SPSS 9.0 statistical package for Windows and, for nominal data, chi-squared-tests were used to compare rates between groups. For continuous data analysis of variance (ANOVA) was performed. When appropriate, a multivariate analysis with binary-regression by Wald was used. Sensitivity and specificity was done using ROC-curves. P < 0.05 was considered significant. From May 1996 to June 2000, 107 patients were included in the study. Besides basic data, all postoperative complications were noted according to a specific definition. Four different risk-scoring systems were used: ASA-classification; the acute physiology and chronic health evaluation (APACHE-II) system; the physiological and operative severity score for enumeration of mortality and morbidity (POSSUM) classification and, finally, the simplified acute physiology score (SAPS) classification.

RESULTS

We found no significant correlation between risk-scores and outcome. None of the scoring systems used was able to predict mortality. The independent factors that influenced the postoperative complication rate were operating time, blood loss, intraoperative assisted ventilation time and age. The endpoint using the relative operating characteristic (ROC) curves analysis was either mortality or morbidity.

CONCLUSIONS

It can be concluded that none of the systems analyzed separately was useful for determining morbidity and mortality. We still lack a system, that can be used preoperatively in an individual case and the vascular surgeon still has to build up his own clinical judgement or to transfer a clinical judgement.